Yes Change request has to be formally submitted in writing then you can do impact assessment and send it for evaluation by CCB, after approval, you must baseline the project management plans and then start the work.

The change request form is submitted to the SME (team) or change control board for review. Once the triple constraint (cost, time, scope) changes are known than he takes it to the customer/sponsor for approval. Once approved it is thing put in the CMS and VISA is performed. The PMP is updated and then integrated in Direct and Manage Project Work.

For minor changes, the PM should first reference the project plan to confirm that the change does meet the criteria for 'minor' for this project. If so, then the PM should document the minor change and have the relevant SME should approve the change as per the plan. Plans should have documented procedures for making minor changes that won't impact critical components of the project (such as the triple constraint). This reduces time spent in unnecessary management effort.